Charged particle exposure apparatus, and a charged particle exposure method

ABSTRACT

The present invention relates to a charged particle beam exposure apparatus, deflecting a charged particle beam formed into a predetermined shape by being passed through a predetermined transmission mask, and irradiating a predetermined location on the surface of a sample with the charged particle beam. The apparatus comprises: a mirror barrel through which the charged particle beam is passed; and an electrostatic deflector, provided in the mirror barrel, for deflecting the charged particle beam. The electrostatic deflector has a plurality of pairs of electrodes, which are made of a conductive material having carbon as a primary element and are embedded in an internal face of an insulating cylinder. The present invention also relates to a method for forming the electrostatic deflector.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a charged particle beam exposureapparatus, and especially to the structure of an electrostaticdeflection electrode; and to a method for manufacturing a chargedparticle beam exposure apparatus.

2. Related Arts

A charged particle beam exposure method using an electron beam or an ionbeam is a known technique for exposing a fine pattern on the surface ofa rectile during the forming of a semiconductor wafer or a mask. Thecharged particle beam exposure apparatus projects a charged particlebeam, which is emitted by a charged particle beam gun, through apredetermined transmission mask, to form a beam whose cross section is apattern to be exposed, and irradiates the surface of a sample with thebeam. In this case, the beam must be deflected to a predeterminedlocation of the sample surface.

For the deflection of the charged particle beam, there is employed acombination of an electromagnetic deflector, which sharply deflects acharged particle beam away from the center axis of the mirror barrel ofan exposure apparatus, and an electrostatic deflector, which deflects acharged particle beam only slightly in a narrow region in the vicinityof the area in which deflection takes place. Although the electrostaticdeflector, which is also called a sub-deflector, provides only a slightdeflection effect , it uses only a comparatively low voltage for beamdeflection, and it can increase the deflection speed. Conversely,although the electromagnetic deflector, which is also called a maindeflector, provides a large deflection effect, deflecting a beamcomparatively sharply, it requires a long setting time for beamdeflection, and, as a result, it reduces deflection speed.

In the mirror barrel of an exposure apparatus, there must be provided,from the top, a charged particle beam gun, a primary transmsison mask, asecondary transmission mask, and the deflectors. In order to reduce thesize of the mirror barrel, the electrostatic deflector and theelectromagnetic deflector are overlapped in the portion wherein aprojection lens is provided, immediately before the position for asample is reached. Taking into consideration the relationship between amagnetic field and an electric field, the electrostatic deflector islocated in a sealed cylinder in which is maintained a vacuum throughwhich the charged particle beam passes, while the electromagneticdeflector and the projection lens (electromagnetic lens) are exposed tothe external atmosphere.

The design for the electrostatic deflector calls for an arrangement ofeight long cylindrical electrodes, for example, with a predeterminedvoltage being applied between each pair of facing electrodes. Byapplying a voltage to the four electrode pairs, it is possible to set asdesired a deflection direction in a narrow sub-deflection region.

The present applicant proposed an electrostatic deflector described inU.S. Pat. No. 5,041,731 or in Japanese Unexamined Patent PublicationNos. Hei 2-247966 and 2-192117.

For an electrode of the electrostatic deflector, a ceramic is shapedinto a cylinder and a groove is formed in the internal surface of thecylinder. The ceramic cylinder is then fired. After that, metal platingis performed to cover the entire internal surface of the cylinder formedof an insulating material, following which the plated layer in thegroove is peeled away by an electric discharge. The electrodes are thuselectrically separated to provide a plurality of pairs of electrodes.Unlike the metal electrodes, the thus produced electrostatic deflectorelectrodes has only plated metal layers on the surface of the ceramic.This can prevent an eddy current, which occurs due to changes in themagnetic field produced by the electromagnetic deflector located outsidethe electrostatic deflector.

However, the electrode structure for which metal plating is performed onthe surface of the ceramic has the following problems.

First, since the procedure for the production of electrodes provides forextruded clay to be dried before it is fired, the shape of the clayelectrodes has changed during being dried and by the time they are readyfor firing. With eight electrodes, for example, the symmetry of theirrelationship will be lost, their sizes will differ, and their bodieswill be twisted and deformed. Furthermore, during the firing process thesame size changes occur. As a result of such size changes, beams aredefocused and the aberrant deflection of beams occurs. In addition, thetwisting of the bodies of the electrodes causes sub-deflectiondirections to be changed.

Second, it is known that since the electrostatic deflection electrodesare positioned the nearest to the sample, a resist made of an organicmaterial coated on the surface of the sample is vaporized whenirradiation with a beam is performed, and as a result a contaminant isdeposited on the surfaces of the electrodes. Also, scattered electronsthat are generated by the irradiation of charged particles may strikeorganic material in the vacuum and cause contaminants to be attached tothe surfaces of the electrodes. Such contamination of the electrodescauses a charge-up on the electrode surfaces; it also results in thedeterioration of the accuracy with which beams are deflected and in thedefocusing of beams.

In order to eliminate the contamination, the present inventors proposeda method for cleaning the surfaces of components in an exposureapparatus by performing plasma excitation of oxygen that is introducedinto the apparatus (e.g., Japanese Patent Application No. Hei 5-138755).With this cleaning method, however, since the application of a highfrequency to a mirror barrel accompanies the generation of plasma, theplating on electrode surfaces is scored by the sputtering of generatedions, and when the cleaning is repeated a number of times, the platedmetal layers will be peeled away and the ceramic will be exposed.Thereafter, a charge buildup will occur relative to the exposed ceramic.It was confirmed by the present inventors that even with a plated layerof 1.5 μm, a charge buildup occurred when cleaning using oxygen wasperformed more than ten but less than twenty times. As a result, thelife expectancy of electrodes is shortened and the ratio relative to theoperation of the exposure apparatus is reduced.

Although the problem concerning plated layers can be resolved by formingelectrodes of metal, as was previously described, metal electrodes willcause an eddy current due to changes in the magnetic field produced byan electromagnetic deflector. With the occurrence of an eddy current,the time constant for the setting time becomes several msec, and inconsonance with this, there is a deterioration in the exposurethroughput.

SUMMARY OF THE INVENTION

To resolve the above shortcomings, it is one object of the presentinvention to provide for an electrostatic deflector an electrodestructure that does not generate an eddy current and that can preventelectrodes from acquiring different sizes and from being deformed, and amethod for manufacturing such an electrostatic deflector.

It is another object of the present invention to provide a chargedparticle beam exposure apparatus that has an electrostatic deflectorhaving electrodes that have a long life and an increased ratio ofoperation.

It is an additional object of the present invention to provide a chargedparticle beam exposure apparatus with which a buildup of a charge doesnot occur even when cleaning using oxygen plasma is performed.

To achieve the above objects, according to the present invention, acharged particle beam exposure apparatus, deflecting a charged particlebeam formed into a predetermined shape by being passed through apredetermined transmission mask, and irradiating a predeterminedlocation on the surface of a sample with the charged particle beam,comprises:

a mirror barrel through which the charged particle beam is passed; and

an electrostatic deflector, provided in the mirror barrel, fordeflecting the charged particle beam, the electrostatic deflector havinga plurality of pairs of electrodes, which are made of a conductivematerial having carbon as a primary element and are embedded in aninternal face of an insulating cylinder.

Since deflection electrodes are formed of a conductive material havingcarbon as a primary element, the surface of the electrodes will not peelaway like a plated metal layer even through cleaning using oxygen plasmais performed. Further, since the resistance of carbon is about a hundredtimes higher than that of metal, an eddy current will not occur on thesurfaces of the electrodes even though changes in a magnetic field areproduced by an electromagnetic deflector, which is located outside theelectrostatic deflector.

Further, according to the above aspect of the present invention, aseparation groove formed between each of the plurality pairs ofelectrodes has an adequately large depth relative to its width. Inaddition, the separation groove formed between each of the plurality ofpairs of electrodes is so shaped that grooves are linked together in atleast two different directions. More specifically, a separation groovehas a first groove segment formed in the direction of the radius of theinsulating cylinder, a second groove segment extending from the firstgroove segment in the circumferential direction of the insulatingcylinder, and a third groove segment extending from the second groovesegment in the direction of the radius.

With a separation groove that is thus shaped, even when the internalface of the insulating cylinder is exposed at the bottom ends of theseparation grooves and reflected electrons of the charged particlesreach there to generate the buildup of a charge, the influence of theelectric field due to the charge can be dissipated by the separationgrooves. As a result, a difference in deflection due to the chargebuildup can be prevented.

To achieve the above objects, according to the present invention, amethod for manufacturing an electrostatic deflector, which is providedin a charged particle beam exposure apparatus for deflecting a chargedparticle beam formed into a predetermined shape by being passed througha predetermined mask, and for irradiating a predetermined location on asurface of a sample with the charged particle beam, comprises the stepsof:

shaping into a cylinder a conductive material containing carbon as aprimary element and firing the cylinder to form a conductive pipe;

forming external grooves having a predetermined shape which extend froman external face of the conductive pipe to an internal position;

inserting the conductive pipe into the insulating cylinder and fixingthe conductive pipe therein;

grinding the internal face of the conductive pipe so as to give theinternal face a substantially cylindrical shape; and

forming internal grooves which extend from the internal face of theconductive pipe to the external grooves, and with which the conductivepipe is separated into a plurality of pairs of electrodes.

More specifically, when the conductive pipe has been formed, first, theseparation grooves are formed in its external face without actualseparation of the pipe and it is inserted into the insulating cylinder.The internal surface of the conductive pipe is then ground so that itsshape becomes a true circle, coaxially formed with the insulatingcylinder. Then, other separation grooves are formed from the internalface of the conductive pipe reaching the external grooves to divide theconductive pipe into a plurality of pairs of electrodes. In this manner,the internal faces of the deflection electrodes, which are mostimportant for an electrostatic deflector, can be accurately sized andnot be twisted. As a result, an accurate deflection electric field canbe provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating the general structure of an electronbeam exposure apparatus;

FIG. 2 is a detailed diagram illustrating the beam exposure section ofthe electron beam exposure apparatus;

FIG. 3 is a diagram illustrating the arrangement of a sub-deflector andits periphery;

FIG. 4. is a perspective view of an example electrode structure of anelectrostatic deflector according to the present invention;

FIG. 5 is a cross sectional view taken along the line AB in FIG. 4;

FIG. 6 is a diagram for explaining a method for manufacturingelectrostatic deflection electrodes;

FIG. 7 is a diagram for explaining the method for manufacturing theelectrostatic deflection electrodes;

FIG. 8 is a diagram for explaining the method for manufacturing theelectrostatic deflection electrodes;

FIG. 9 is a diagram for explaining the method for manufacturing theelectrostatic deflection electrodes;

FIG. 10 is an enlarged cross sectional view of the deflection electrodesthat are finally produced;

FIG. 11 is a cross sectional view of an example of electrostaticdeflection electrodes having a different shape;

FIG. 12 is a cross sectional view of another example of electrostaticdeflection electrodes having a different shape;

FIG. 13 is a cross sectional view of an additional example ofelectrostatic deflection electrodes having a different shapes;

FIG. 14 is a cross sectional view of a further example of electrostaticdeflection electrodes having a different shape; and

FIG. 15 is a cross sectional view of yet another example ofelectrostatic deflection electrodes having a different shape.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred embodiment of the present invention will now be describedwhile referring to the accompanying drawings. The technical scope of thepresent invention is not, however, limited to the preferred embodiment.General structure of a charged particle beam exposure apparatus!

FIG. 1 is a diagram illustrating the general structure of an electronbeam exposure apparatus. The present invention can be applied to anyexposure apparatus that utilizes a charged particle beam, and in thisembodiment, an electron beam exposure apparatus is employed as anexample. The exposure apparatus comprises an exposure unit 10 and acontrol unit 50. Pattern data stored in a storage medium 51, such as adisk, are transmitted to the control unit 50 via an interface 53, andare converted into the drive signals that are required for exposure. Inconsonance with the drive signals, driving of lenses and deflectors inthe exposure unit 10 is performed.

FIG. 2 is a detailed diagram illustrating the exposure unit 10. Thestructure of the exposure unit 10 can be clearly understood from theexplanation given while referring to FIG. 2.

The exposure unit 10 will now be described. An electron beam gun 10, anelectron beam generator, is constituted by a cathode electrode 11, agrid electrode 12, and an anode electrode 13. An electron beam isprojected through alignment coils 36 for axis matching, and lenses 16A(not shown in FIG. 1) to a first slit 15. The first slit 15 normally hasa rectangular aperture by which the electron beam is shaped into arectangle. The rectangular beam enters a slit deflector 17 after passingthrough lenses 16B. The slit deflector 17 is controlled in consonancewith a correction deflection signal S1, and is employed for delicatecorrection of positions. Reference numeral 37 denotes alignment coils.

In order to shape an electron beam and give it a predetermined pattern,a transmission mask 20 is used that has a plurality of transmissionholes, such as a rectangular opening and a block pattern opening havinga specific pattern. Therefore, electromagnetic lenses 18 and 19, anddeflectors 21 through 24 are located above and below the transmissionmask 20 in order to guide the electron beam to the location of a desiredpattern opening. It should be noted that the transmission mask 20 ismounted on a horizontally movable stage.

The irradiation of a wafer W by the thus shaped electron beam iscontrolled by a blanking electrode 25 to which a blanking signal SB istransmitted. Reference numeral 38 denotes other alignment coils.

The electron beam projected in consonance with the control exercised bythe blanking electrode 25 passes through lenses 26 and a round aperture27. The round aperture 27 is one aperture type, and the degree to whichit can be opened is adjustable. With this aperture 27, control isprovided for the convergence of the half angle of the electron beam. Thefinal beam shape is adjusted by a re-focal coil 28 and electromagneticlenses 29. A focus coil 30 focuses the electron beam on a surface to beexposed, and a sting coil 31 corrects for astigmatism.

At the final stage, the electron beam is reduced to an exposure size byprojection lenses 32, and the correct location on the surface of thewafer-W is irradiated with the electron beam by a main deflector 33 anda sub-deflector 34, which are controlled in accordance with exposedposition determination signals S2 and S3, respectively. The maindeflector 33 is an electromagnetic deflector and the sub-deflector 34 isan electrostatic deflector.

The control unit 50 will now be described. Data for an exposure patternare stored in the memory 51, are read by a CPU 52, and are computed by apredetermined program. The acquired drawing data are transmitted via theinterface 53 to a data memory 54 and a sequence controller 60. Thedrawing data include at the least data for a position on the wafer Wwhich is to be irradiated with the electron beam, and mask datadesignating a pattern on the transmission mask 20.

A pattern controller 55 supplies, to the deflectors 21 through 24,position signals P1 through P4, each indicting one of the transmissionholes on the transmission mask 20 according to the data for the maskthat is to be drawn. The pattern controller 55 also computes correctionvalue H that corresponds to a difference in shape between a pattern tobe drawn and a designated transmission hole, and transmits thecorrection value H to a digital/analog converter/amplifier 56. Theamplifier 56 transmits a correction deflection signal S1 to a deflector17. In addition, the pattern controller 55 controls a mask shiftingmechanism 57 to move the transmission mask 20 horizontally in consonancewith the position of selected transmission holes.

In response to a control signal from the pattern controller 55, ablanking control circuit 58 transmits a blanking signal SB to theblanking electrode 25 via the amplifier 59. The blanking electrode 25controls the irradiation with an electron beam.

The sequence controller 60 receives drawing position data from theinterface 53, and controls a drawing sequence. A stage moving mechanism61 horizontally moves a stage 35 in consonance with a control signalfrom the sequence controller 60. The distance that the stage 35 is movedis detected by a laser interferometer 62, and is transmitted to adeflection control circuit 63. The deflection control circuit 63supplies deflection signals S2 and S3 to the main deflector 33 and thesub-deflector 34 in accordance with the moving distance of the stage andthe exposed position data, which is provided by the sequence controller60. Generally, an electron beam is deflected by the main deflector 33 ina deflection field that is, for example, 2 to 20 mm square, while thebeam is deflected by the sub-deflector 34 in a sub-field that is, forexample, 100 μm square.

In FIG. 2, the detailed structure of the electron beam exposureapparatus that is shown differs from the structure in FIG. 1, with anoxygen supply device 8 supplying oxygen gas to chambers 2, 3a, 3c and 3bvia mass flow sensors 2, 3, 4 and 5, respectively. A plasma is generatedby providing a supply of oxygen and by connecting a high frequencygenerator (not shown) to the internal electrodes, and with this oxygen,the surfaces of the components are cleaned. In other words, activatedoxygen is provided by generating a plasma, and contaminants are removedfrom the surfaces of the components by using the activated oxygen.

FIG. 3 is a diagram illustrating the arrangement of the sub-deflector 34and its periphery. The sub-deflector 34 is a portion which directlyfaces the wafer W, a sample, and one of those wherein most contaminantstend to be deposited by a gas generated by a resist coated on thesurface of the wafer W.

A cylindrical component 56a composed of insulating material is locatedon the sub-deflector 34. The cylindrical component 56a has a hollow,circular shape, and a flange 57 at its top end. The flange 57 is fixedto a frame member 60 of the exposure apparatus by an O ring 59. Acylindrical component 56b also composed of the insulating material islocated under the sub-deflector 34, and has a flange 58 that is providedin the same manner. The flange 58 directly faces the wafer W, as asample, and is positioned at the lowermost end of the mirror barrel. Theflanges 57 and 58 are plated with a conductive film and are grounded.

The sub-deflector 34 is covered with another cylindrical item 61 that isformed of the insulating material. A flange 62 is located at the lowerend of the cylindrical item 61, and is fixed to a frame member 64 by anO ring 63. In the cylindrical component 61 a vacuum is maintained. Theframe members 60, 64 and 66 are formed of insulating material. The maindeflector 33 shown in FIG. 2 is provided outside of the cylindrical item61.

As for the sub-deflector 34, a plurality of pairs of electricallyinsulated electrodes are arranged inside a cylinder formed of insulatingmaterial. An electric field is distributed in an arbitrary direction byapplying a voltage to one pair of opposing electrodes, and in thisfashion an electron beam is deflected.

Electrodes of an electrostatic deflector!

FIG. 4 is a perspective view of the electrode structure of theelectrostatic deflector 34 according to the present invention. FIG. 5 isa cross sectional view taken along the line AB in FIG. 4.

In the electrode structure, eight electrodes 342, made of a conductivematerial containing carbon as its primary element, are provided insidean insulating cylinder 341 made of an insulating material, such asceramic. The conductive material is produced by shaping a mixture ofcarbon and a binder into a cylinder and firing it. The thus producedmaterial is a glassy carbon wherein carbon crystals have becomeamorphous. Therefore, almost all, at least 90%, of the glassy carbon iscarbon. GC20, a product name of Tokai Carbon Co., Ltd., is preferable assuch glassy carbon.

Since the resistivity of carbon is approximately one hundred timesgreater than that of metal, an eddy current is not caused at thesurfaces the electrodes of the conductive material, containing carbon asits primary element, even when the electrodes are affected by a magneticfield produced by the main deflector 33, i.e., the electromagneticdeflector. Further, since the plating of a metal film is not performed,the peeling of plating caused by sputtering will not occur, even as aresult of conventional plasma cleaning.

According to this example of the electrode arrangement, a glassy carboncylinder is fired and separation grooves 343 are formed by the electrondischarge method, so that the insulation-separated eight electrodes 342are provided. As is apparent from the cross sectional view in FIG. 5,each of the separation grooves 343 is constituted by groove segments343a and 343c extending from the center axis X of the cylinder towardthe radius, and a groove segment 343b extending in the circumferentialdirection so as to link together the groove segments 343a and 343c. Theshape of the separation groove 343 can be variously modified. It ispreferable that the exposed internal face of the insulating cylinder 341be separated as far as possible, via the separation grooves 343, fromthe center portion through which an electron beam is projected. Inaddition it is preferable that the ratio of the depth of the separationgroove 343 to its width (aspect ratio=depth/width) be as great aspossible.

This is because, with the above electrode arrangement, it is required,even if a charge buildup (accumulation of a charge) occurs at theinsulating portion of the internal face of the insulating cylinder 341that is exposed by forming the separation grooves 343, an electric fielddue to the charge buildup will not affect the center area through whichan electron beam passes.

A method for manufacturing the electrode arrangement will now beexplained while referring to FIGS. 6 through 9.

First, glassy carbon solidified by mixing it with a binder is extruded,dried, and fired to provide a cylindrical pipe 345 shown in FIG. 6.L-shaped grooves are formed first in the outer surface of the pipe 345by the electron discharge method, wherein a discharge is generated bybringing a metal line 346 into contact with the pipe 345 while at thesame time applying a high voltage to the metal line 346.

FIG. 7 is a cross sectional view of the pipe 345 in which are formedeight of the L-shaped grooves comprising segments 343a and 343b. Thegroove segment 343a is so formed that it extends inward from the outersurface of the pipe 345 along the line of the radius, and the groovesegment 343b is so formed that it extends from the groove segment 343ain the circumferential direction.

Sequentially, as is shown in FIG. 8, the conductive pipe 345 is insertedinto the insulating cylinder 341, which is made of a ceramic containingalumina (Al₂ O₃) as its primary element. A plurality of holes 346 formedin the insulating cylinder 341 are linearly arranged in the axialdirection. The conductive pipe 345 is so inserted that the groovesegments 343a are located between the holes 346 that are arranged in theaxial direction, as is shown in FIG. 9.

An adhesive is applied through the holes 346 to bond the insulatingcylinder 341 to the conductive pipe 345. Reference numeral 344 in FIG. 9denotes a bonded face. It is preferable that the adhesive not spread tothe groove segments 343a.

An internal face 346 of the conductive pipe 345 is ground so as to becoaxially formed relative to the external diameter of the insulatingcylinder 341 and so as to form a true circle. Since separations arelater formed in the conductive pipe 345 to provide eight electrodes, anda distribution of an electric field is provided upon the application ofa voltage to each pair of opposing electrodes, it is necessary toaccurately locate the faces of the opposing electrode pairs in order toprovide the precise electric field distribution.

Using the electron discharge method shown in FIG. 6, the groove segments343c shown in FIG. 5 are formed extending outward from the internal face346 of the conductive pipe 345 along the radius, and the eight separatedeflection electrodes are thereby provided. Since the separatedeflection electrodes are bonded to the insulating cylinder 341 at thebonding face 344 by an adhesive, they maintain their relative positions.

As is described above, the pipe made of a conductive material is shapedand fired, and the resultant pipe is inserted into and fixed to theinsulating cylinder 341. The internal face of the pipe is ground so thatit is coaxially formed with the insulating cylinder 341 and so that itforms a true circle. Thereafter the groove segments 343a are formed inthe internal face by the electron discharge method to divide the pipeinto electrodes. Therefore, even when a change in the shape or atwisting of the body occurs during the shaping and firing of theconductive pipe 345, the shape of the internal face of the electrodesthat is finally produced will conform to design values. As a result, anelectrostatic deflector can be provided that ensures the electrodes aresymmetric and that has excellent deflection accuracy.

Further, with the above described manufacturing method, first theseparation groove segments 343a and 343b are formed from the externalside of the conductive pipe 345, and then the separating groovessegments 343c are formed from the inside and link up with the groovesegments 343b. Therefore, during electron discharge processing, carbonflakes generated during the formation of the separation grooves will notremain on the internal face of the insulating cylinder 341, or theelectrodes 342 will not be formed by insufficient separation of the pipe345.

FIG. 10 is an enlarged cross sectional view of the deflection electrodesthat are finally produced. When the separation grooves 343 are formedfrom the inside by the electron discharge method after the pipe 345 isinserted into the insulating cylinder 341, it is expected that at aportion 347 in FIG. 10, the pipe 345 will be insufficiently separated,or that carbon flakes will be attached and remain. Such a phenomenoncauses insufficient insulative separation and a charge buildup in theattached carbon. Such a phenomenon will not occur when the abovedescribed manufacturing method is used.

In addition, the aspect ratio (depth of the groove/width) of theseparation groove 343 is large, for example at least 5:1. Even if thereflected electrons that accompany the irradiation of the electron beamEB reach the bottom of the separation grooves 343 and cause a chargebuildup at the portion 347 in FIG. 10, the influence of the chargebuildup on the electric field is dissipated by the deep separationgrooves 343, and the change buildup has no effect on the portion that isirradiated to the electron beam EB. In other words, the electric fieldproduced by a charge is confined within the separation grooves 343. Inthe above embodiment, further, since the separation grooves 343 are bentat two places, a great shielding field effect is obtained.

In FIGS. 11 through 15 are shown different example shapes for theelectrostatic deflection electrodes. These electrode structures are thesame as that wherein the electrodes are formed by inserting theconductive pipe 345, containing carbon as its primary element, into theinsulating cylinder 341. The differences between these electrodesstructures are the shapes of the separation grooves 343. Although theshapes of the separation grooves 343 differ, however, the internal faces346 of the separated electrodes comprise eight arcs, which are obtainedby equally dividing the internal circle.

In the example in FIG. 11, separation grooves 343 are shaped so thatthey incline toward the radius. As was previously described, the aspectratio is sufficiently great that even if charges are accumulated at theinternal face of the insulating cylinder 341, at the bottoms of theseparation grooves, the shielding effect provided by the grooves 343 issufficient to prevent the electron beam from being affected by theelectric fields. Further, the aspect ratio of the separation grooves 343is increased by the equivalent of the inclination. As was previouslydescribed, first, the segment of the separation groove 343 is formedfrom the external face up to the middle of the pipe 345. Then, after thepipe 345 is inserted into the insulating cylinder 341, the other segmentof the separation groove 343 is formed from the inside of the pipe 345,so that it is linked up with the groove segment formed from the externalface.

The example shown in FIG. 12 shows separation grooves 343 formedlinearly along the radius. With the separation groove 343 that has asmall diameter, an adequate shielding effect can be obtained. Theformation of the separation grooves 343 is easy.

The example in FIG. 13 shows L-shaped separation grooves 343. Aseparation groove segment 343e is formed from the outer face of aconductive pipe 345 and a separation groove 343d is formed from theinside.

The example shown in FIG. 14 shows S-shaped separation grooves 343. Onehalf of the separation groove 343 is formed from the outer surface ofthe conductive pipe 345 and the other half of the separation groove 343is formed from the inside the pipe 345. The grooves 343 having an Sshape provide a great shielding effect.

The example in FIG. 15 shows L-shaped separation grooves 343. Aseparation groove segment 343f, close to the internal face of theelectrode 342, is extended along the radius and a separation groovesegment 343g, close to the outer face, is extended perpendicularly fromthe groove segment 343f. These segments 343f and 343g are formedrespectively from the outer face and the internal face.

Various other modifications can be employed for the electrode structure.The principle of the present invention is that electrostatic deflectionelectrodes, at the surfaces of which an eddy current does not occur andwhich are highly resistant to damage during plasma cleaning, are highlyaccurately formed and sized by a process during which a pipe is formedof a conductive material containing carbon as its primary element and isinserted to an insulating cylinder, and the internal face of theconductive pipe is then shaped and separation grooves are formed fromthe inside for insulative separation of the pipe. Therefore,modifications of the electrode shapes that fall within the scope of theprinciple of the invention correspond to the technical scope of thepresent invention.

As is described above, according to the present invention, sinceelectrostatic deflection electrodes are formed of a conductive materialcontaining carbon as a primary element, the resistivity of which ishigher than that of metal, an eddy current does not occur on theelectrodes, even though there are changes in a magnetic field producedby an electromagnetic deflector, which is located outside theelectrostatic deflector. Therefore, the electrostatic deflector of thepresent invention satisfactory serves as a sub-deflector for deflectinga beam at high speed.

Further, since electrodes are formed of a conductive element containingcarbon, the conventional problems that occur when plasma etching is usedto clean the interior, such as the scoring of electrode surfaces and thepeeling away of plated electrode layers, are eliminated. In addition,even when cleaning using ozone is performed, the surfaces of carbonelectrodes are scored at most on the order of μm. Further, during plasmacleaning using oxygen, the surfaces of the electrodes are abraded onlyon the same order. As a result, the condition of the electrostaticdeflection electrodes can be maintained for a long time.

Furthermore, since after the conductive material is shaped and fired,the internal face is again processed to increase its coaxial accuracyand to form it into a true circle, and then the electrode separationgrooves are formed, the sizing of the internal faces of the electrodesis very accurately performed, and deflection accuracy is enhanced.

What we claim are:
 1. A charged particle beam exposure apparatus,deflecting a charged particle beam formed into a predetermined shape bybeing passed through a predetermined transmission mask, and irradiatinga predetermined location on the surface of a sample with the chargedparticle beam, comprising:a barrel through which the charged particlebeam is passed; and an electrostatic deflector, provided in the barrel,for deflecting the charged particle beam, the electrostatic deflectorhaving a plurality of pairs of electrodes, which are made of aconductive material having carbon as a primary element and are embeddedin an internal face of an insulating cylinder.
 2. A charged particlebeam exposure apparatus according to the claim 1, wherein;a separationgroove formed between each of the plurality pairs of electrodes has anadequately large depth relative to its width.
 3. A charged particle beamexposure apparatus according to the claim 1, wherein;a separation grooveformed between each of the plurality of pairs of electrodes is so shapedthat grooves are linked together in at least two different directions.4. A charged particle beam exposure apparatus according to the claim 3,wherein;the separation groove has a first groove segment formed in thedirection of the radius of the insulating cylinder, a second groovesegment extending from the first groove segment in the circumferentialdirection of the insulating cylinder, and a third groove segmentextending from the second groove segment in the direction of the radius.5. A method for exposing a charged particle beam, by deflecting acharged particle beam formed into a predetermined shape by being passedthrough a predetermined transmission mask, and irradiating apredetermined location on the surface of a sample with the chargedparticle beam, said method comprising:deflecting a charged particle beamby applying a predetermined voltage between a pair of electrodes of anelectrostatic deflector, wherein the electrostatic deflector is providedin a barrel through which the charged particle beam is passed and has aplurality of pairs of electrodes, which are made of a conductivematerial having carbon as a primary element and are embedded in aninternal face of an insulating cylinder.